What is the sliding scale for Humalog (insulin lispro) dosing based on blood glucose levels?

Sliding Scale Insulin Should Not Be Used as the Primary Inpatient Diabetes Management Strategy

Sliding scale insulin (SSI) alone is inferior to scheduled basal-bolus insulin regimens for hospitalized patients and should be avoided as monotherapy. Multiple high-quality guidelines consistently demonstrate that SSI results in worse glycemic control, higher rates of treatment failure, and does not reduce hypoglycemia compared to scheduled insulin regimens 1.

Why Sliding Scale Insulin Is Inadequate

The evidence against SSI as primary therapy is compelling:

• Higher treatment failure rates: SSI resulted in 19% treatment failure compared to 0% with basal-bolus and 2% with basal-plus regimens in hospitalized patients with type 2 diabetes 1
• Reactive rather than proactive: SSI treats hyperglycemia after it occurs rather than preventing it, leading to suboptimal glycemic control 1
• Inadequate for achieving targets: Both regular and lispro insulin sliding scales fail to achieve recommended glycemic targets when used as the only inpatient treatment 2

Recommended Approach: Basal-Bolus Insulin Regimen

For hospitalized patients requiring insulin, use a scheduled basal-bolus regimen consisting of long-acting basal insulin plus rapid-acting prandial insulin (such as Humalog/lispro) before meals, supplemented with correctional doses 1.

Typical Dosing Structure:

• Basal insulin: 50% of total daily dose given as once-daily long-acting insulin (glargine, detemir, or degludec) 1
• Prandial insulin: Remaining 50% divided equally before three meals using rapid-acting insulin (lispro, aspart, or glulisine) 1
• Correctional insulin: Add supplemental rapid-acting insulin based on pre-meal glucose readings 1

Starting Doses:

• Insulin-naive patients: Begin with 0.4-0.5 units/kg/day total daily dose 1
• Previously on insulin: Use 80% of home dose initially to reduce hypoglycemia risk 1

When Correctional ("Sliding Scale") Insulin May Be Appropriate

Correctional insulin as a supplement to scheduled insulin is acceptable in limited circumstances 1:

• Patients with well-controlled diabetes (HbA1c <7%) on diet or low-dose oral agents alone 1
• Patients with mild hyperglycemia who are NPO with no nutritional replacement 1
• Patients newly started on or tapering off corticosteroids 1
• As a temporary bridge while titrating scheduled insulin regimens 1

Simplified Correctional Dosing Example:

For patients requiring occasional correction while on scheduled insulin 1:

• Pre-meal glucose >250 mg/dL: give 2 units rapid-acting insulin
• Pre-meal glucose >350 mg/dL: give 4 units rapid-acting insulin
• Discontinue when not needed daily 1

Humalog (Insulin Lispro) Specific Considerations

Humalog should be administered immediately before meals (within 15 minutes) as part of a basal-bolus regimen, not as sliding scale monotherapy 1.

• Onset: 15 minutes, making it ideal for prandial coverage 1
• Peak: 30-90 minutes 1
• Duration: 3-5 hours 1
• Dosing: Typically 4-10 units per meal initially, adjusted based on carbohydrate intake and pre-meal glucose 1

Critical Pitfalls to Avoid

• Never use SSI alone in hospitalized patients with established diabetes requiring insulin therapy - this consistently results in worse outcomes 1
• Do not give rapid-acting insulin at bedtime - this increases nocturnal hypoglycemia risk without benefit 1
• Avoid aggressive titration targeting glucose <140 mg/dL - the recommended inpatient target is 140-180 mg/dL for most patients to balance efficacy and hypoglycemia risk 1, 3
• Do not continue SSI for prolonged periods - transition to scheduled insulin within 24-48 hours 1

Alternative Approaches for Stable Patients

For patients with mild-to-moderate hyperglycemia (glucose <200 mg/dL) who are stable and eating regularly 1:

• Continue home oral medications if appropriate 1
• Basal insulin plus DPP-4 inhibitor with correctional insulin 1
• Basal-plus regimen: Basal insulin with one prandial dose before the largest meal 1

These approaches require fewer injections while maintaining superior glycemic control compared to SSI alone 1.